Pipe coupling



me M, i947., P, Q WURZBURGER MEE @t PIPE COUPLING Filed Sep'r.. 27, 1944Patented Jen. 14, 1947 UNITED STATES PATENT OFFICE rms coUPLING Paul n.wmbiirger, cleveland ohio u l Application september 27, 1944, serial Ne.556,004

(ci. ass-122) 1 Claim. l y. l This invention relates to tube or pipecouplings and more particularly to that' type of tube or pipe y 2manufacturing point of view, to structures of this coupling employing asleeve or packing member provided with a forward internal sharp edge ofa material harder than the pipe to be connected avoid this objection byone of three expedients.

and which is adapted to be constricted. when forced against a 4cammingshoulder or flared mouth of a body member ofthe coupling in such a waythat the-internal sharp edge cuts or bites into the outer surface of thetube or pipe to be coupled to form its own seat, providing asatisfactory hydraulic and mechanical Joint.

Couplings of this general nature are disclosed in the United StatesPatents Nos. 2,139,413 granted December 6, 1938, 2,171,217 grantedAugust 29, 1939, 2,201,404 granted May.21, 1940, 2,211,856 grantedAugust 2'0, 1940, and 2,230,116 granted January 28, 1941.

It has been found in the use of these couplings that certaindifliculties have been experienced, for example, when it is desired tocouple a tube or pipe of relatively hard material such as steel or otherferrous material to a body member which may be softer than the steel ofthe pipe. It is necessary, of course, that the packing ring, which isintended to bite or cut into the material of the pipe be of somematerialwhich is either inherently harder than that of the pipe or can be madeso by suitable treatment. When this material is used in conjunction witha camming -surface of a flaring mouth in a softer body member, there isa danger that instead of the body Y member camming the packing ring intobiting or cutting engagement with the tube, the packing ring will biteinto the camming surface itself, which is undesired, thus making ofa-satisfactory coupling or so distorting the camming surface that thecoupling may not be uncoupled and again recoupled in a satisfactory way.To avoid this all' the above mentioned patents with the exception of thelast one, resort to the expedient of providing a packing ring having anundercut portion, so that the cutting edge was disposed at a substantialdistance inward from the end of the packing ring and the portion oi thepacking ring arranged to engage the camming surface was thin in respectto that portion opposite the cutting edge.` This was an eifectivesolution to the problem and is entirely satisfactory in use. However,themechanical operation of forming packing rings in this way is quitediilicult, as it requires very accurate machining on parts which aresometimes quite small. The resultant dimculty and expense thereofpresents a very real objection, from the either preventing the Vtionalmachining operations.

type.

The last patent referred to, 2,230,116, seeks to In Figs, 2 and 3 thereis shown a body .portion having a hardened inner camming surface or`'flared mouth. This is difficult ii not impossible to produce on theinside of a brass member and hence is undesirable. In Fig. 4 there isshown an insert which may be of relatively hard material, i. e. materialharder than that of the packing ring. This complicates the problem ofmanufacture as it requires the making of an additional member which mustbe carefully machined and then threaded into the body member proper.

The form shown in Fig. 5 illustrates a lining cf hard material locatedwithin the flaredl mouth of the relatively soft body member cc whichalso is difficult to construct in order to provide satisfactoryoperation.

My present invention seeks to avoid these various difficultiesv by arelatively simpler expedient, which is cheaper from the manufacturer'spoint of view, yet entirely satisfactory in` operation and use andrequires no additional members and no 4special hardening of `any of theparts. More speciiically I have discovered a comparatively simplemathematical relationship of the several parts, which, if followed, willresult in overcoming the difllculties above referred to by taking intoaccount the dimensions and hardnesses of the several parts and vwhichthen determines as a matter of design the limiting dimensions orrelationships which may be used to attain the desired results withoutexpensive additional parts,

special hardenings or diiiicult and costly addi- The provision of acoupling having mathematical relationships or proportions in accordancewith these teachings is a primary object of the present invention.

I have further discovered that in order to prevent the packing ring frombiting into the cam- A.ming surface, it is desired that the outerleading edge thereof be rounded, in accordance with a specificmathematical relationship taking into consideration the moduli ofelasticity oi? the material of the packing ring and that of the aredmouth arranged to contact it. The provision of a packing ringconstructed in accordance with this novel relationship is a furtherobject to the present invention.

A more specific object of the present invention in thisrespect is t0provide this curvature in such a manner that it will not unduly weakenthe packing ring, particularly that portion thereto tl'iose skilled inthe art `the coupled or sealed position;

manufacture and easy to assemble.

andrea of which is subject to the compressive forces incident to thecamming operation required to complete a coupling For this purpose Ihave provided a specic relationship by which the curved portion isrestricted to the outer half of the thickness Aof-Ithe packing ring andbears a desired specific tangential relation to the outer surfacethereof. A /f While the invention may be embodiedin other forms ofapparatus, I have `illustrated in drawing what I now consider to be' apreferred type of coupling for carrying my invention into practice.Other forms or variations will occur after .I have explained myinvention herein. g

Referring to the drawing: Figure l. is a longitudinal section of acoupling embodying my invention associated withehtube or pipe about tobe coupled;

Fig. 2 is a fragmentary view Fig. 3 is an enlarged fragmentary view ofthe parts in an undesirable relation; i

Fig. d is a similar view showing similar parts inl a permissiblerelation; e if Fig. 5 is a diagrammatic showing cf the end o fj' thecutting sleeve in reference to the rounding di the corner-:engageablewith theiiared mouth; and Figs. 6 and 'l show modiedforms of the cutlting sleeves-'or packing rings.

it will be noted that y Referring to the drawing,

the l0 of thefpi'ts 121120 pling, as well as the tube T, will usuallybut not 'necessarily be made of metal.

To facilitate explanation of my invention and clarify the appendedclaim, I shall .refer to that and has been deformed or constricted bythe fiaring mouth M after the parts have been assembled and the nut Ntightened. As indicated above, the opposite end of thepacking ring maylikewise be provided with a similar active zone to provide for 'itsreversibility in use and so as to make the device substantiallyfool-proof in assembling.

In order satisfactorily to perform its cutting function the packing ringS is made of material which'is harder than that of the tube T with whichthe coupling is to` be employed. Preferably "the packing ring S is oflowjcarbon steel, surfacev hardened, when the tube to be coupled is ofsteel. The body member B and the nut N can be made of any suitablematerial, preferably inetallic. The body member B need not necessarily lbe of a material harder than that of the packing the particular form ofcoupling illustrated` com mises a body portion B externally threaded toree' ceive a nut Naud provided at its end with a coneshaped or daredmouth der 6. A tube T with which the coupling is to be employed isinserted in the body portion until its entering end/abuts the shouldert. The vnut has a shoulder t, shown sloping in the drawing.- for thepurpose of cooperating with a packing ring S so as to force the latterlongitudinally towards the body portion B andto compress its rear end 'lagainst the tube T as the nut is tightened up. The sleeve ifor packingring S is shown in Mterminating in a shoul- 3 ring S; it may be of thesame hardness or softer. The definite relationship (mentioned above)between certain physical characteristics that Q should not be exceededand which, if obeyed, gives valuable and unobvious results; will now beexplained.

caumg the armen hardness number of the A ness of that for a i0millimeterball at 3,000 kilothe form of a hollow cylinder of generallyuniw, d5

form internal and external diameters prior to use. Preferably, althoughnot necessarily, Iso construct vthe packing ring S that either endthereof may be employed asthe active end or zone, whereby assembly isfacilitated. Each leaddo ing end of the packing ring S comprises aninternal cutting edge, of which one is indicated at I, and an externalcurved portion 3 for cooperation with the sloping wall of the flaredmouth M of the body portion B. The intended operation is substantiallyas follows:

In assembling, the tube 'I' is placed in the body portion B until, asstated above. its leading end abuts the shoulder 6 of the body portion.The

sleeve S is placed in the position shown in Fig. 1, a@

likewise lthe nut N, and the latter is tightened on the body portion Buntil the parts assume the relative position shown in Fig. 2 where itwill be seen Athat the forward movement vof the packing ring S, i. e.its movement toward the body memc5 ber B has caused the leading innercutting edge 4 to cut, dig or plow into the outer surface of the tube Tstriking up an annular ridge 5 around the entire periphery of the tubeT.

This coupling, if constructed according to my invention, provides a'very effective and emcient duid-tight seal betweenthe'tube Tand thebody member B and is comparatively inexpensive to The component parte orelements of the touw is f` grams) and where a represents the angle of inclination of the dared or conical mouth M measured from the axis of thecoupling as indicated in Fig. 1, and i is the wall thickness in inchesin the active zone or end of the packing ring S cated in Fig. l, therelationship which I have discovered is expressed by the followingequation:

in.' non HS *cos 2a For any particular valuesv of Brinell hardnessnumber (HB) of the body member and (Hs) the few thousandths of an inch,leaving a. soft core within the hardened packing ring, then the value ofHs should be taken as one-half the measured surface Brinell hardnessnumber.

I have found that if the above relationship is observed, i. e. the valueof the right hand term of the equation is equal 'or smallerthan that ofthe left hand term, the end of the packing ring S will notdeleteriouslyv affect the conical mouth or camming shoulder M whenforced into it and it is not necessary to provide the active end of `thepacking ring E; vwith'special yielding means,

or to hardenthe surface of the flaring mouth M deeper, or to a stateharder than the packing ring.

When the forward end of the cutting ring forcibly contacts the surfaceof the flared mouth or funnel orcamming shoulder M of the body of the asindi# As shown in Fig. when the desired radius is sr'nall in respect tothe thickness of the sleeve so that 'the rounding takes the shape or thearc 2t,`

the arc may conveniently be struck from a center lying in a line at 45?to the inner and outer surfaces of the sleeve as at 2i. The roundedcorner 20 will bear smoothly on the flared mouth and fairly close to thefront face 30 of the forward end of the sleeve S. as will be apparentupon inspection of Fig. 5, where the line M2 represents the flaredmouth. If, however, the prescribed radius should .be somewhat greaterthan the respective parts of the sleeves other than the active endsthereof.

In accordance with the provisions of the patent statutes, I have hereindescribed the principle of i operation of my invention, together withthe apparatus which I now consider to represent the best embodimentsthereof, but I desire to have it understood that the apparatus disclosedis only lillusizrativeand that the invention can be carried lout-byother.l means. Also, while it is designed tou'se the various featuresand elements in the z'comblnation and relations described, some ofthickness oi the sleeve S as I have illustrated by the arc 22 struckfrom a center point 123, the condition would be less desirable, in mypresent view, by virtue, oi excessively thinning down the sleeve aboveand adjacent to the cutting edge I.

To accommodate such larger radii and to prev serve a substantial squareheight above the cutting edge i as up to the point 3l, for example,

I prefer to move thecenter from which such radius is struck forwardlyfrom the point 2d as to the point 2d so that the rounding of the edgewill follow the arc 25, or substantial tangency, retaining, of course,its tangency to the outer suriace of the sleeve.` This permits thesquare front surface between the points 4 and 3i to be substantiallyhalf the thickness o! the sleeve, as' I prefer, and will permit the arc25to have its initial line'oi contact with'the dared mouth of the bodyto be well forward on the curve as at about the point 26 so that theinwardly (downwardly as viewed in Fig. 5) acting forces will be reason-"these may be altered and others omitted, and

some oi.' the 'features of each modiiicationr'nay be embodied in theothers, without interfering with the more general results outlined, andthe invention extends to such use within the scope of the appendedclaim.

What4 is claimed is: y

Means for coupling a pipe oi relatively hard material to a iitting -ofrelatively soft material, wherein said iitting has a shoulder forengagement with the end of the pipe to be. coupled thereto andv asubstantially frusta-conical, outwardly ,flared recess therein,comprising a ring ofmaterial harder than that of the pipe having acurved leading edge adapted slidingly to engage with the inner conicalsurface of said recess, and means cooperating withsaid ring and saidfitting i'or forcing said ring into camming engagement with the conicalsurface of said recess, the angle of the ably adjacent to the `frontface 30 of the sleeve and the cutting edge l.

In Figs. 6 and 7 I have illustrated two modified forms o! cutting ringsor sleeves Si and Sz.

The'active ends ci these rings are constructed in f accordance with theteaching 0I the instant speciiication. The thickened portion Il! o! .the

`sleeve Si and the thickened .portion 4l of thel sleeve S2 are eachdisposed to give strength to the corneal surface of said recessinrespect to the common axis' of 'said pipe and said fitting and thethickness of said ring being jointly determined in accordance with thehardness of the surface oi said recess andthat oi the surfacecontactingportion of said ring so as to prevent undesired deformation of thesurface of said recess upon the completion of the coupling such aswill-prevent effective re-use of the coupling.

PAUL D. WURZBURGER.'

